Dwingeloo 2

Dwingeloo 2
Observation data (J2000 epoch)
Constellation	Cassiopeia
Right ascension	02h 54m 08.47s[1]
Declination	+59° 00' 19.1"[1]
Helio radial velocity	94 ± 1.5 km/s[2]
Galactocentric velocity	241 km/s[2]
Distance	~10 Mly (3 Mpc)[3]
Group or cluster	IC 342/Maffei
Type	IAm
Apparent dimensions (V)	2' × 0'.8[1]
Apparent magnitude (V)	16.21 (V-band)[4]
Notable features	Companion of Dwingeloo 1
See also: Galaxy, List of galaxies

Dwingeloo 2 is a small irregular galaxy discovered in 1996 and located about 10 million light-years away from the Earth. Its discovery was a result of Dwingeloo Obscured Galaxy Survey (DOGS) of the Zone of Avoidance. Dwingeloo 2 is a companion galaxy of Dwingeloo 1.^[2]

Dwingeloo 2 was first detected at radio wavelengths from the 21 cm emission line of neutral atomic hydrogen (known to astronomers as HI) in the course of follow-up observations after the discovery of Dwingeloo 1.^[2] Dwingeloo 2 is thought to be a member of the Maffei 1 group, a group of galaxies adjacent to the Local Group.^[3]

The visible radius of Dwingeloo 2 is approximately 2′, which at the distance of 3 Mpc corresponds to about 2 kpc.^[1] The neutral hydrogen is detected as far as 3.2 kpc from the center. The mass of the galaxy within this radius is estimated at 2.3 billion Solar masses. The total mass of the galaxy is about five times less than that of Dwingeloo 1.^[2]

Dwingeloo 2 has a a well defined rotating disk inclined at approximately 69° with respect to observer. The galaxy recedes from the Milky Way at the speed of about 241 km/s.^[2] The distribution of the neutral hydrogen in Dwingeloo 2 is quite irregular. Its total mass is estimated at about 100 million Solar masses. The irregular structure of Dwingeloo 2 is likely related to its interaction with nearby much larger galaxy Dwingeloo 1, which lies at the distance of only 24 kpc from Dwingeloo 2.^[2]

References

1. ^ ^{a b c d} "NASA/IPAC Extragalactic Database". Results for Dwingeloo 2. http://nedwww.ipac.caltech.edu/. Retrieved 2011-10-06. 
2. ^ ^{a b c d e f g} Burton; Verheijen, M. A. W.; Kraan-Korteweg, R. C.; Henning, P. A. (1996). "Neutral hydrogen in the nearby galaxies Dwingeloo 1 and Dwingeloo 2". Astronomy and Astrophysics 309: 687–701. arXiv:astro-ph/9511020. Bibcode 1996A&A...309..687B. http://adsabs.harvard.edu/abs/1996A%26A...309..687B. 
3. ^ ^{a b} Karachentsev, I. D. (2005). "The Local Group and Other Neighboring Galaxy Groups". The Astronomical Journal 129: 178. doi:10.1086/426368.  edit
4. ^ Buta, R. J.; McCall, M. L. (1999). "The IC 342/Maffei Group Revealed". The Astrophysical Journal Supplement Series 124: 33. doi:10.1086/313255.  edit

External links

• Dwingeloo 2 – Galaxy